SA94140618B1 - Method and apparatus for the preparation of 1,2-dichloroethane by direct chlorination - Google Patents

Abstract

Abstract: In the reaction of ethylene with chlorination to form 1,2- dichloroethane ( 1,2- ) EDC dichloroethane if the catalyst components of sodium chloride and iron chloride are used in a molar ratio of less than 0.5, it is obtained EDC is of sufficiently high purity to allow direct conversion to vinyl chloride.By maintaining the prescribed molar ratio the reaction can be carried out very efficiently in terms of equipment and energy consumption, eg by evaporating some of the EDC in an expansion vessel.

Description

0: A process and apparatus for the preparation of YY-dichloroethane 1,2-dichloroethane by direct chlorination: Full description Background of the invention: In the so-called direct chlorination process, 0-dichloroethane 1, 2-dichloroethane, referred to below as EDC © by the reaction of ethylene and chlorine; The addition reaction is catalyzed by the metal halides that act as Lewis acids and a J halide of the first main group of the periodic table. In the process described in calla patent 6901398 NL-A, the metal halide with the preferred Lewis acid behavior is iron (ID) chloride. The metal from the first group of the periodic table 0 is preferred to have a higher atomic number, VY (sodium, specifically lithium, z). The molar ratio of the halide, which has the behavior of Lewis acid and halide halide is a metal of the first group of the periodic table of the elements being between:7 and 1:7 : EP 0 111 203 B2 describes a process in which the catalyst used is tetrachloroferrate and not Ale ; for example For example, tetrachloroferrate sodium »or the components are used according to the quantitative chemical relations.In the patent DE 4103 281 AL D 4M

The catalyst used is iron (II) chloride mixed with sodium chloride in a molar ratio of 1: 9 to .1: 1. General description of the invention: It has now been found that chlorination Direction of ethylene © takes place successfully when a molar ratio of sodium chloride to iron (II) chloride is maintained during the reaction is less than 1,# . Preserving this cag dal allows the reaction to be carried out so that it produces EDC of great purity to be used directly to form vinyl chloride without distillation of high-boiler materials. add to that ; The process of the invention is not high costs in relation to 0 equipment and energy consumption. The preferred embodiments of the invention and associated advantages will be explained in detail. The reaction medium used is preferably liquid EDC; The reactants are fed into the circulating EDC. It is not necessary to use chlorine in liquid form; Whereas the process of the invention can be carried out under Vo mild conditions; Especially those that have mist a pressure where gaseous chlorine can be used. Therefore the maximum preferred pressure is 1 bar ¢ preferably between 1.4 and oT 6 bar which is stabilized using an inert gas; A pillow of nitrogen is preferred, the reaction temperature is from 500 to 1007 C; Distinctively, from 0 to 16 m. The temperature and pressure are set separately so that the reaction takes place under the EDC boiling point dg a preferred embodiment of the invention; Pass all or better some of the EDC into an expansion vessel held under vacuum; The enthalpy of the EDC vapor causes a portion of the EDC to vaporize. The evaporated EDC is WIA from the catalyst and after condensation is 4

£ has a purity of at least 799.90; So that it can be fed directly to the fission reaction to form vinyl chloride. This enables the removal of waste water that would be necessary for catalyst removal in conventional processes; conducting without pressure drop or evaporation EDC; As well as drip drying 0 required for EDC, it is preferable that the pressure in the expansion vessel be from 17 to 7 absolute bar. This low pressure is produced and maintained using conventional fans or pumps; hereinafter referred to as a vacuum pump 0 and if the denatured vacuum pump is not used to carry the gaseous EDC the latter is condensed using a suitable device; add) 0 is hereafter referred to as file ; It is collected in a bowl. Exploiting the heat of reaction for molecular evaporation of EDC and maintaining the reaction temperature in the aforementioned preferred range results in a significant reduction in a all of the refrigerant. : the part of the unevaporated EDC containing the catalyst and the remainder in the vo expansion device is returned to the EDC circuit; This is possible because the reaction constitutes a very small part of the by-products. Thus, the returned ©7200 contains small amounts of hydrogen chloride. The polluting gas is practically chlorine-free. Particularly preferred operation 6 in which only a portion of the EDC ¢ preferably a relatively small amount 7 is poured into the expansion vessel; It has the advantage (ila) that a secondary reactor to convert the remaining ethylene is not necessary. on it; Seal removal and recycling can be provided even in this preferred embodiment of the invention as they are not of high cost.

> Also ¢ ethylene yield can be increased or ethylene loss can be reduced by returning the off-gas from the ethylene-containing expansion vessel to the reaction from a vacuum pump downstream point using a suitable compressor ; A liquid-jet compressor is preferred; which is fixed at the bottom ° of the reactor; Re-reaction of ethylene with chlorine. The rotary jet of the preferred compressor is an excess stream (partial stream) from the EDC circulation. The remaining quantities of ethylene can also be used to produce energy by burning the polluted gas, preferably to extract hydrogen chloride 0 The invention is presented also a device that is suitable for the process of the invention. It is Ligue with its preferred embodiments; Shown in fig. Detailed Description: 0 The apparatus of the invention includes: 10 reactors (1); lines dad (?) and (¥) for ethylene chlorine; respectively; and the best (£) for inert gas; : Line (0) for the expansion vessel (6) which is under reduced pressure and has a Ye line (V) to remove the evaporated product and line (A) to recover the non-evaporated product; it is preferable to connect with the melting vessel (4) and Jy is preferred by pump (01); and line (11) is used to return the partial product stream; which is preferably managed by pump (VY) and a cooler or heat exchanger (OF) 4 m

: Line 0 (VY) of the EDC vapor is driven via the cooler (VE) of the vacuum pump (V0) and from the cooler (V€) the line (V1) leads to the receiver (VV ) for the liquefied EDC. usefully; The device includes a line (1A) from (pressure side) of the vacuum pump (V0) via the compressor (V4) to the reactor (1) to return the residual quantities of unreacted ethylene. (01) and (YY) are lines for draining the polluted gas. : If the operation is carried out for long periods, we must ensure that the ratio of sodium chloride to iron chloride, ron (IIT) chloride, is of the invention. If Mia » iron chloride Jalairon (IT) chloride is intercalated into the plant; eg » via corrosion, the corresponding amounts of sodium chloride must be measured ¢ appropriately from the dissolution vessel (4) ¢ otherwise Distilled EDC will decrease in purity or by-product formation will increase Circulating EDC ¢ has a purity greater than 799 and is clear 1 i.e. no solid particles can be identified and is only slightly colored It is not necessary to overflow a portion of The following examples illustrate the invention: EXAMPLES 1 Up to; Direct chlorination takes place in a reactor (1) having a volume of 7 0 Tad and a filling level of 1 78 by volume. The pressure is maintained at 6.94 bar in line (4) and the temperature is maintained at 70°C. The reaction medium EDC is a liquid containing 0 ppm iron chloride. iron (IIT) chloride Sodium chloride is given to the reaction medium through a dissolving vessel (9) until it reaches the desired molarity of chloride Sodium Z 4M

Sodium chloride to iron (II) chloride (referring to the table below) This ratio is maintained during the reaction. The reactor (1) is fed with 7000 cubic meters of measure J h of ethylene by means of (V) all and the corresponding amount of gaseous chlorine: chlorine by bal (©).The drained product stream (partial stream)© is connected by line (*) into a downstream expansion vessel d(T). WY pressure absolute bar In this, Ad tons of EDC are evaporated and drawn through the line (Y).The aforementioned BDC is catalyst-free and has the purity given in the table, which allows the manufacture of EDC directly to vinyl chloride By-product level 1; Evaporated in expansion vessel (1) returns via line (A) and pump (01) to reactor (1). The main product stream is fed via line (VY) and pump (VY) to line (A) and returns, if necessary, via the coolant (VF) to the reactor (1) vo in the table; example 1 is a comparative example (without adding sodium chloride ( ; while the examples 'even' are of the invention.

Claims (1)

A ileal elements by reacting ethylene 1,2-dichloroethane AW ?-¢ 1 to prepare lee -1 1 + sodium chloride in the presence of a sodium chloride catalyst chlorine with chlorine ethylene Y It involves maintaining the molar ratio of cron (II) chloride (iron chloride - v dD) wal to sodium chloride of NaCl 1 below 4.0 during the whole reaction; Where 11 of iron chloride ° bar is being carried out and the aforementioned pressure gauge is stabilized using a cushion 1 reaction after pressure + of an inert gas. 7; where the molar ratio is from 1 ?- the process as stated in claim number 1 in iron (II) chloride yall to sodium chloride Y cto up to 0.1 par of y where the reaction takes place for oY or 1 the operation as stated in Claims No. =F) M. Veo up to 900 at Y the process as mentioned in Claim No. ; where the temperature is in —¢ 1 : up to 60 C. 1 bounds of Y ; Where the reaction takes place at a pressure of 1 process as mentioned in protection element No. -# 1 bar. 1,7 up to 1,4 of 7;0; Where all or part of the process 0 passes as described in Claim No. 1-1 to a container that maintains it under pressure 1,2-dichloroethane - "0 ?- dichloroethane » 1 low; the distillate is separated and the remaining ¥ is returned to the process. 1,2- dichloroethane £4 d 9 1 7- The process as mentioned in Claim No. 1; where the reaction medium is 1; ?- cyclic dichloroethane -1,2. 1 +-_operation as described in claim 1; where it feeds chlorine as a gas. 1 4- The process as mentioned in Claim No. 7; Where the low pressure Y mentioned in the previous container is from 1.7 to 1.7 bar absolute.